Is it ensure, insure, or assure?
fuchsin fuch·sin (fyōōk'sĭn) or fuch·sine (-sĭn, -sēn')
Any of various red to purple-red rosanilin dyes used as bacterial and histological stains.
basic fuchsin n.
A mixture of rosanilin and pararosanilin chlorides used to stain cellular elements, certain tissues, and bacteria, especially tubercle bacilli.